Displaying publications 1 - 20 of 119 in total

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  1. [Identification and sequence analysis of E gene of Dengue virus type 2 strain isolated from patient serum in Shenzhen]
    Yang F, He JF, Xian HX, Zhang HL, He YQ, Yang H, et al.
    Zhonghua Yu Fang Yi Xue Za Zhi, 2009 Sep;43(9):798-802.
    PMID: 20137564
    To isolate and identify the pathogen of Dengue fever from Shenzhen city in 2005 - 2006, and to analyze the molecular characteristics of the isolated Dengue virus strain as well as to explore its possible origin.
    Matched MeSH terms: Dengue/virology*
  2. Fulltext First round of external quality assessment of dengue diagnostics in the WHO Western Pacific Region, 2013
    Pok KY, Squires RC, Tan LK, Takasaki T, Abubakar S, Hasebe F, et al.
    Western Pac Surveill Response J, 2015 Jun 30;6(2):73-81.
    PMID: 26306220 DOI: 10.5365/WPSAR.2015.6.1.017
    Accurate laboratory testing is a critical component of dengue surveillance and control. The objective of this programme was to assess dengue diagnostic proficiency among national-level public health laboratories in the World Health Organization (WHO) Western Pacific Region.
    Matched MeSH terms: Dengue/virology
  3. Fulltext Structure-Based Design of Antivirals against Envelope Glycoprotein of Dengue Virus
    Anasir MI, Ramanathan B, Poh CL
    Viruses, 2020 03 26;12(4).
    PMID: 32225021 DOI: 10.3390/v12040367
    Dengue virus (DENV) presents a significant threat to global public health with more than 500,000 hospitalizations and 25,000 deaths annually. Currently, there is no clinically approved antiviral drug to treat DENV infection. The envelope (E) glycoprotein of DENV is a promising target for drug discovery as the E protein is important for viral attachment and fusion. Understanding the structure and function of DENV E protein has led to the exploration of structure-based drug discovery of antiviral compounds and peptides against DENV infections. This review summarizes the structural information of the DENV E protein with regards to DENV attachment and fusion. The information enables the development of antiviral agents through structure-based approaches. In addition, this review compares the potency of antivirals targeting the E protein with the antivirals targeting DENV multifunctional enzymes, repurposed drugs and clinically approved antiviral drugs. None of the current DENV antiviral candidates possess potency similar to the approved antiviral drugs which indicates that more efforts and resources must be invested before an effective DENV drug materializes.
    Matched MeSH terms: Dengue/virology*
  4. Complete genome sequence analysis of dengue virus type 2 isolated in Brunei
    Osman O, Fong MY, Devi S
    Virus Res, 2008 Jul;135(1):48-52.
    PMID: 18406488 DOI: 10.1016/j.virusres.2008.02.006
    In a previous study, we have reported the detection and isolation of dengue virus in Brunei (Osman, O., Fong, M.Y., Devi, S., 2007. A preliminary study of dengue infection in Brunei. JJID 60 (4), 205-208). DEN-2 was the predominant serotype followed by DEN-1. The full genomic sequences of 3 DEN-2 viruses isolated during the 2005-2006 dengue incident in Brunei were determined. Twenty-five primer sets were designed to amplify contiguous overlapping fragments of approximately 500-600 base pairs spanning the entire sequence of the viral genome. The amplified PCR products were sent for sequencing and their nucleotides and the deduced amino acids were determined. All three DEN-2 virus isolated were clustered in the Cosmopolitan genotype of the DEN-2 classification by Twiddy et al. This work constitutes the first complete genetic characterization of three Brunei DEN-2 virus strains.
    Matched MeSH terms: Dengue/virology*
  5. Fulltext Antiviral activity of four types of bioflavonoid against dengue virus type-2
    Zandi K, Teoh BT, Sam SS, Wong PF, Mustafa MR, Abubakar S
    Virol J, 2011;8:560.
    PMID: 22201648 DOI: 10.1186/1743-422X-8-560
    Dengue is a major mosquito-borne disease currently with no effective antiviral or vaccine available. Effort to find antivirals for it has focused on bioflavonoids, a plant-derived polyphenolic compounds with many potential health benefits. In the present study, antiviral activity of four types of bioflavonoid against dengue virus type -2 (DENV-2) in Vero cell was evaluated. Anti-dengue activity of these compounds was determined at different stages of DENV-2 infection and replication cycle. DENV replication was measured by Foci Forming Unit Reduction Assay (FFURA) and quantitative RT-PCR. Selectivity Index value (SI) was determined as the ratio of cytotoxic concentration 50 (CC50) to inhibitory concentration 50 (IC50) for each compound.
    Matched MeSH terms: Dengue/virology
  6. Fulltext Geraniin extracted from the rind of Nephelium lappaceum binds to dengue virus type-2 envelope protein and inhibits early stage of virus replication
    Abdul Ahmad SA, Palanisamy UD, Tejo BA, Chew MF, Tham HW, Syed Hassan S
    Virol J, 2017 11 21;14(1):229.
    PMID: 29162124 DOI: 10.1186/s12985-017-0895-1
    BACKGROUND: The rapid rise and spread in dengue cases, together with the unavailability of safe vaccines and effective antiviral drugs, warrant the need to discover and develop novel anti-dengue treatments. In this study the antiviral activity of geraniin, extracted from the rind of Nephelium lappaceum, against dengue virus type-2 (DENV-2) was investigated.

    METHODS: Geraniin was prepared from Nephelium lappaceum rind by reverse phase C-18 column chromatography. Cytotoxicity of geraniin towards Vero cells was evaluated using MTT assay while IC50 value was determined by plaque reduction assay. The mode-of-action of geraniin was characterized using the virucidal, attachment, penetration and the time-of-addition assays'. Docking experiments with geraniin molecule and the DENV envelope (E) protein was also performed. Finally, recombinant E Domain III (rE-DIII) protein was produced to physiologically test the binding of geraniin to DENV-2 E-DIII protein, through ELISA competitive binding assay.

    RESULTS: Cytotoxicity assay confirmed that geraniin was not toxic to Vero cells, even at the highest concentration tested. The compound exhibited DENV-2 plaque formation inhibition, with an IC50 of 1.75 μM. We further revealed that geraniin reduced viral infectivity and inhibited DENV-2 from attaching to the cells but had little effect on its penetration. Geraniin was observed to be most effective when added at the early stage of DENV-2 infection. Docking experiments showed that geraniin binds to DENV E protein, specifically at the DIII region, while the ELISA competitive binding assay confirmed geraniin's interaction with rE-DIII with high affinity.

    CONCLUSIONS: Geraniin from the rind of Nephelium lappaceum has antiviral activity against DENV-2. It is postulated that the compound inhibits viral attachment by binding to the E-DIII protein and interferes with the initial cell-virus interaction. Our results demonstrate that geraniin has the potential to be developed into an effective antiviral treatment, particularly for early phase dengue viral infection.

    Matched MeSH terms: Dengue/virology
  7. Fulltext Molecular epidemiology demonstrates that imported and local strains circulated during the 2014 dengue outbreak in Guangzhou, China
    Li G, Pan P, He Q, Kong X, Wu K, Zhang W, et al.
    Virol Sin, 2017 Feb;32(1):63-72.
    PMID: 28120220 DOI: 10.1007/s12250-016-3872-8
    The dengue virus (DENV) is a vital global public health issue. The 2014 dengue epidemic in Guangzhou, China, caused approximately 40,000 cases of infection and five deaths. We carried out a comprehensive investigation aimed at identifying the transmission sources in this dengue epidemic. To analyze the phylogenetics of the 2014 dengue strains, the envelope (E) gene sequences from 17 viral strains isolated from 168 dengue patient serum samples were sequenced and a phylogenetic tree was reconstructed. All 17 strains were serotype I strains, including 8 genotype I and 9 genotype V strains. Additionally, 6 genotype I strains that were probably introduced to China from Thailand before 2009 were widely transmitted in the 2013 and 2014 epidemics, and they continued to circulate until 2015, with one affinis strain being found in Singapore. The other 2 genotype I strains were introduced from the Malaya Peninsula in 2014. The transmission source of the 9 genotype V strains was from Malaysia in 2014. DENVs of different serotypes and genotypes co-circulated in the 2014 dengue outbreak in Guangzhou. Moreover, not only had DENV been imported to Guangzhou, but it had also been gradually exported, as the viruses exhibited an enzootic transmission cycle in Guangzhou.
    Matched MeSH terms: Dengue/virology*
  8. Antibody neutralization and viral virulence in recurring dengue virus type 2 outbreaks
    Wong SS, Abd-Jamil J, Abubakar S
    Viral Immunol, 2007 Sep;20(3):359-68.
    PMID: 17931106
    Outbreaks involving dengue viruses (DENV) of the same genotype occur in a cyclical pattern in Malaysia. Two cycles of outbreaks involving dengue virus type 2 (DENV-2) of the same genotype occurred in the 1990s in the Klang Valley, Malaysia. Sera of patients from the first outbreak and sera of mice inoculated with virus from the same outbreak had poorer neutralization activity against virus of the second outbreak. Conversely, patient sera from the second outbreak showed higher neutralization titer against virus of the early outbreak. At subneutralizing concentrations, sera of mice immunized with second outbreak virus did not significantly enhance infection with viruses from the earlier outbreak. Amino acid substitution from valine to isoleucine at position 129 of the envelope protein (E), as well as threonine to alanine at position 117 and lysine to arginine at position 272 of the NS1 protein, differentiated viruses of the two outbreaks. These findings highlight the potential influence of specific intragenotypic variations in eliciting varied host immune responses against the different DENV subgenotypes. This could be an important contributing factor in the recurring homogenotypic dengue virus outbreaks seen in dengue-endemic regions.
    Matched MeSH terms: Dengue/virology
  9. Vector competence of Malaysian Aedes albopictus with and without Wolbachia to four dengue virus serotypes
    Joanne S, Vythilingam I, Teoh BT, Leong CS, Tan KK, Wong ML, et al.
    Trop Med Int Health, 2017 09;22(9):1154-1165.
    PMID: 28653334 DOI: 10.1111/tmi.12918
    OBJECTIVE: To determine the susceptibility status of Aedes albopictus with and without Wolbachia to the four dengue virus serotypes.

    METHODS: Two newly colonised colonies of Ae. albopictus from the wild were used for the study. One colony was naturally infected with Wolbachia while in the other Wolbachia was removed by tetracycline treatment. Both colonies were orally infected with dengue virus-infected fresh blood meal. Dengue virus load was measured using quantitative RT-PCR at four-time intervals in the salivary glands, midguts and ovaries.

    RESULTS: Wolbachia did not significantly affect Malaysian Ae. albopictus dengue infection or the dissemination rate for all four dengue virus serotypes. Malaysian Ae. albopictus had the highest replication kinetics for DENV-1 and the highest salivary gland and midgut infection rate for DENV-4.

    CONCLUSION: Wolbachia, which naturally exists in Malaysian Ae. albopictus, does not significantly affect dengue virus replication. Malaysian Ae. albopictus is susceptible to dengue virus infections and capable of transmitting dengue virus, especially DENV-1 and DENV-4. Removal of Wolbachia from Malaysian Ae. albopictus would not reduce their susceptibility status.

    Matched MeSH terms: Dengue/virology
  10. Fulltext Dengue serotype surveillance among patients admitted for dengue in two major hospitals in Selangor, Malaysia, 2010-2011
    Ab-Fatah M, Subenthiran S, Abdul-Rahman PS, Saat Z, Thayan R
    Trop Biomed, 2015 Mar;32(1):187-91.
    PMID: 25801270 MyJurnal
    Dengue serotype surveillance is important as any changes in serotype distribution may result in an outbreak or increase in severe dengue cases. This study aimed to determine circulating dengue serotypes in two hospitals in Selangor. Serum samples were collected from patients admitted for dengue at these two major public hospitals i.e. Hospital Sungai Buloh (HSB) and Hospital Tunku Ampuan Rahimah (HTAR) between November 2010 and August 2011 and subjected to real-time RT-PCR using SYBR® Green. All four dengue serotypes were detected in samples from both hospitals. The predominating serotype was dengue 1 in samples from both hospitals (HSB, DENV-1; 25.53 % and HTAR, DENV-1; 32.1 %).
    Matched MeSH terms: Dengue/virology*
  11. Fulltext Monoclonal antibody-escape variant of dengue virus serotype 1: Genetic composition and envelope protein expression
    Chem YK, Chua KB, Malik Y, Voon K
    Trop Biomed, 2015 Jun;32(2):344-51.
    PMID: 26691263 MyJurnal
    Monoclonal antibody-escape variant of dengue virus type 1 (MabEV DEN-1) was discovered and isolated in an outbreak of dengue in Klang Valley, Malaysia from December 2004 to March 2005. This study was done to investigate whether DEN152 (an isolate of MabEV DEN-1) is a product of recombination event or not. In addition, the non-synonymous mutations that correlate with the monoclonal antibody-escape variant were determined in this study. The genomes of DEN152 and two new DEN-1 isolates, DENB04 and DENK154 were completely sequenced, aligned, and compared. Phylogenetic tree was plotted and the recombination event on DEN152 was investigated. DEN152 is sub-grouped under genotype I and is closely related genetically to a DEN-1 isolated in Japan in 2004. DEN152 is not a recombinant product of any parental strains. Four amino acid substitutions were unique only to DEN 152. These amino acid substitutions were (Ser)[326](Leu), (Ser)[340](Leu) at the deduced E protein, (Ile)[250](Thr) at NS1 protein, and (Thr)[41](Ser) at NS5 protein. Thus, DEN152 is an isolate of the emerging monoclonal antibody-escape variant DEN-1 that escaped diagnostic laboratory detection.
    Matched MeSH terms: Dengue/virology*
  12. Fulltext Temperature related storage evaluation of an RT-PCR test kit for the detection of dengue infection in mosquitoes
    Ooi CP, Rohani A, Zamree I, Lee HL
    Trop Biomed, 2005 Jun;22(1):73-6.
    PMID: 16880757
    The rapid detection of dengue infection in mosquito vectors is important for early warning to forestall an outbreak. Reverse Transcriptase-Polymerase Chain Reaction (RT-PCR) provides a rapid method for dengue detection in man and mosquitoes. An RT-PCR kit developed by the Medical Entomology Unit, Institute for Medical Research to detect dengue infection in mosquitoes, was tested for its shelf life at 3 storage temperatures: room temperature, refrigerator and freezer. Test kits were tested once every 3 days for kits stored at room temperature, and once every week for those stored at refrigerator and freezer temperatures. The results showed that the test kit could only be stored above its recommended storage temperature of -20 degrees C for not more than 3 days. DNA 100 bp markers in the kits appeared to be stable at the tested temperatures and were usable up to the 20th day when stored at 2 degrees C and below.
    Matched MeSH terms: Dengue/virology
  13. Serotyping of dengue virus in 2016-17 outbreak in Kudat, Sabah, Malaysia
    Aung TS, Gintarong T, Balingi DB, Emran A, Thein TT, Chua TH
    Trop Biomed, 2020 Mar 01;37(1):58-65.
    PMID: 33612718
    An outbreak of dengue in Kudat, northern Sabah in 2016-2017 provided an opportunity to investigate the circulating serotypes of dengue viruses of cases at Hospital Kudat. Between September 2016 and December 2017, a total of 156 dengue positive sera (tested positive by either NS1 antigen, or IgM and IgG antibody rapid test) were collected from dengue patients who had acute fever and showed signs and symptoms suggestive of dengue. RNA was extracted from the sera using QIAamp RNA Blood Mini Kit, and molecular amplification was performed using one-step RT-PCR kit, followed by nested PCR using HotStart Taq master mix kit with the primers of the dengue C-prM gene. There were 81 (52%) male and 75 (48%) female cases. The age group with the highest number of cases was the 10-19 years old, while the youngest infected was 8 months old and the oldest was 83 years old. RT-PCR results showed 88 sera dengue positive, 48 infected with a single serotype while another 40 with multiple serotypes. All four DENV serotypes were co-circulating during the outbreak period and DENV-1 was predominant. Molecular analysis also indicated 69.2%, 50.0%, 51.9% and 48.9% respectively of the NS1, IgM, IgG and IgM and IgG positive sera were RT-PCR positive for dengue. High number of cases were seen in December 2016, February and May 2017. The dengue outbreak might be related to switching of predominant serotype from DENV 4 to DENV 1.
    Matched MeSH terms: Dengue/virology
  14. Neurovirulence of four encephalitogenic dengue 3 virus strains isolated in Malaysia (1992-1994) is not attributed to their envelope protein
    Fong MY, Yusup R, Yusof R, Lam SK
    Trans R Soc Trop Med Hyg, 2004 Jun;98(6):379-81.
    PMID: 15099995
    The amino acid sequences of the envelope (E) protein of four encephalitogenic and five non-encephalitogenic dengue 3 virus strains isolated in Malaysia were determined and compared. Multiple sequence alignment revealed a high degree of similarity in the E protein of the strains suggesting that neurovirulence of these four encephalitogenic strains is not attributed to this protein.
    Matched MeSH terms: Dengue/virology*
  15. Molecular typing of dengue viruses circulating on the East Coast of Peninsular Malaysia from 2005 to 2009
    Vinomarlini G, Rogayah T, Saraswathy TS, Thayan R, Apandi M, Fauziah MK, et al.
    Southeast Asian J. Trop. Med. Public Health, 2011 Jan;42(1):94-9.
    PMID: 21323170
    From 2005 to 2009, the Institute for Medical Research (IMR), Kuala Lumpur, Malaysia received 488 serum and blood samples from hospitalized patients on the East Coast of Peninsular Malaysia, suspected of having dengue infection. In this study we determined the prevailing dengue serotypes using a real time polymerase chain reaction assay (RT-PCR). All 4 dengue virus serotypes were found circulating during the study period; however the predominant serotype varied. In 2005 and 2006, the predominant serotypes circulating were DENV-1 and DENV-3, in 2007, DENV-1 and DENV-2 were predominant, and in 2008 and 2009, DENV-3 was the predominant serotype.
    Matched MeSH terms: Dengue/virology
  16. Fulltext Impact of larviciding with a Bacillus thuringiensis israelensis formulation, VectoBac WG, on dengue mosquito vectors in a dengue endemic site in Selangor State, Malaysia
    Lee HL, Chen CD, Masri SM, Chiang YF, Chooi KH, Benjamin S
    Southeast Asian J. Trop. Med. Public Health, 2008 Jul;39(4):601-9.
    PMID: 19058596
    The field bioefficacy of a wettable granule (WG) formulation of Bacillus thuringiensis israelensis (Bti), VectoBac WG (Bti strain AM65-52) against dengue vectors, Aedes aegypti and Ae albopictus; was evaluated in a suburban residential area (TST) and in a temporary settlement site (KB) in the state of Selangor, Malaysia. Pre-control ovitrap surveillance of the trial sites indicated a high population of both types of Aedes mosquitoes. The populations were monitored continuously by weekly ovitrapping. Bti was sprayed biweekly at a dosage of 500 g/ha by using a mist-blower. The spray application was targeted into outdoor larval habitats. If required, Bti formulation was also applied directly into indoor water-holding containers at 8 g/1,000 l. Based on ovitrap surveillance, a significant reduction in Aedes populations was evident 4 weeks after initiating the first Bti treatment. The ovitrap index (OI) and the larvae density decreased drastically in both trial sites. In TST, the indoor OI was significantly reduced from 57.50 +/- 7.50% to 19.13 +/- 5.49% (p<0.05), while the outdoor OI decreased from 38.89 +/- 11.11% to 15.36 +/- 5.93%. In KB, similarly, the OI was significantly reduced by more than half, from 66.66 +/- 6.67% to 30.26 +/- 2.99% (p< 0.05). In all cases, the reduction in OI was paralleled by reduction in larval density.
    Matched MeSH terms: Dengue/virology
  17. Fulltext Sequence analysis of E/NS1 gene junction of dengue virus type 2 isolated in Brunei
    Osman O, Fong MY, Devi S
    Southeast Asian J. Trop. Med. Public Health, 2008 Jan;39(1):62-78.
    PMID: 18567445
    A preliminary study of dengue infection in Brunei between 2005 and 2006 showed that dengue 2 was the predominant serotype. A total of five DEN-2 isolates were isolated and maintained in the mosquito cell-line, albopictus C6/36. The sequence spanning the envelope and non-structural protein 1 (E/NS1) junction (positions 2311 to 2550) of the isolates were determined and analysed at the amino acid and nucleotide levels. Alignment of the 240 nucleotide sequences among the five isolates showed changes occurring at 7 positions (2.9%) of the region. All but one nucleotide substitution (position 2319, amino acid 742 V --> F) were found at the 3rd position of the codons and were silent mutations. Amino acid homology ranged from 98% to 100%. Sequence divergence of the Brunei isolates varied from 5% to 6.6% compared with dengue-2 prototype New Guinea C strain. Comparison of the Brunei DEN-2 isolates with sixty-five other strains placed them in a cluster containing Indonesian strains isolated in 1973, 1978 and 2004 and Malaysian strains isolated in 1996, 1998 and 1999 in genotype group IV.
    Matched MeSH terms: Dengue/virology
  18. Effects of ribavirin and hydroxyurea on oral infection of Aedes aegypti (L.) with dengue virus
    Lee HL, Phong TV, Rohani A
    Southeast Asian J. Trop. Med. Public Health, 2012 Nov;43(6):1358-64.
    PMID: 23413698
    This study was conducted to determine the inhibitory effects of ribavirin and hydroxyurea on dengue virus replication in Aedes aegypti mosquitoes. Female Ae. aegypti mosquitoes were infected with dengue-2 virus and fed ribavirin at a dose of 0.3 mg/ml and/or hydroxyurea at a dose of 6 mg/ml via artificial membrane feeding technique. The virus in infected mosquitoes was isolated using C6/36 cell culture. Peroxidase-antiperoxidase (PAP) staining was used to detect dengue-infected C6/36 cells and to quantify the level of infection by determining the presence of infected cells. In mosquitoes treated with ribavirin alone, hydroxyurea alone or both drugs in combination had reductions in dengue infection rates of 87.72, 89.47 and 95.61%, respectively. The mortalities of female Ae. aegypti mosquitoes fed with these drugs were significantly higher than the control. Ribavirin also had an inhibitory effect on the fecundity of female Ae. aegypti mosquitoes.
    Matched MeSH terms: Dengue/virology
  19. Fulltext Effect of sublethal dosages of malathion on the oral susceptibility of Aedes aegypti to dengue-2 virus infection
    Lee HL, Argubano RA, Ahmad R
    Southeast Asian J. Trop. Med. Public Health, 1997 Sep;28(3):664-5.
    PMID: 9561626
    Matched MeSH terms: Dengue/virology
  20. Fulltext Detection of dengue virus from field Aedes aegypti and Aedes albopictus adults and larvae
    Ahmad R, Ismail A, Saat Z, Lim LH
    Southeast Asian J. Trop. Med. Public Health, 1997 Mar;28(1):138-42.
    PMID: 9322296
    Mosquito adults and larvae were collected from dengue high risk areas and transported to the laboratory for identification. Identified mosquitos were pooled according to the species, date and locality and stored at -70 degrees C. A total of 1,385 pools of Aedes albopictus and 267 pools of Ae. Aegypti were collected from major towns in 12 states in Peninsular Malaysia. Virus isolation was carried out using cell culture (C6/36 clone) of Ae. albopictus and detection of dengue virus by the peroxidase anti-peroxidase staining. All positive isolations were further re-confirmed by the reverse transcriptase-polymerase chain reaction (RT-PCR). Most of the pools were negative with PAP staining and RT-PCR. However, 11 mosquito pools were positive with PAP staining. On the other hand, samples from Terengganu, Pulau Pinang and Johor were positive using both methods.
    Matched MeSH terms: Severe Dengue/virology
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